The structure and function of human interferon (IFN) genes in experimental systems such as poly(I).poly(C)-induced human diploid fibroblasts (FS-4) and bromodeoxyuridine (BrdUrd)-treated, Sendai virus-induced human lymphoblastoid cells (Namalwa) continue to command our interest. We have succeeded in detecting novel human IFN-alpha and beta mRNAs using translation assays (e.g., the 1.8 kb IFN-alphaL and the 1.3 kb IFN-beta2 mRNAs); in assigning distinct biologically active IFN-beta mRNA species to human chromosomes 2, 5 and 9; in isolating several novel IFN-beta-related human genomic DNA clones (in addition to the classical IFN-beta gene that resides on chromosome 9); and, in turn, in assigning some of these to human chromosomes 2 (clone lambdaB3) and 4 (clone lambdaB4) using blot-hybridization procedures. I. Human IFN locus on chromosome 2. Our highest research priority is to study exhaustively the IFN-beta locus on chromosome 2 (14 kb of nucleotide sequence data are already available), its transcription products (e.g., the 1.8 kb IFN-beta3 mRNA), the IFN protein(s) derived therefrom and the conditions necessary for its expression. DNA at this locus consists of subdomains highly related to IFN-beta1 and undergoes somatic rearrangement and amplification. The possibility that this DNA rearrangement may be a necessary requirement for the expression of the IFN locus on chromosome 2 is exciting. II. Human IFN locus on chromosome 9. The demonstration by us that the classical IFN-beta1 gene and the alpha1-cross-hybridizing genes (all located on chromosome 9) are constructed of DNA subunits leads to a series of structure-activity studies on IFN proteins expressed by genetically engineered IFN-alpha1 and beta1 "half-genes" (as well as by subdomains of lambdaB3 DNA). The molecular details of biologically important apparent read-through transcription across these genes will also be investigated. The regulation of the stability of IFN-beta1 mRNA in cell-free systems derived from FS-4 cells induced with poly(I).poly(C) in the presence and absence of "superinducing" agents will also be investigated. III. Other human IFN loci. We shall also characterize and study several additional IFN-beta-related human genomic DNA clones that we have already isolated (e.g. lambdaB4 assigned to chromosome 4) and continue our efforts to obtain cDNA clones corresponding to human IFN-alphaL and beta2 mRNAs. The proposed research plan is designed to explore the complex molecular biology of the human IFN system and is likely to provide a basis for the production of novel human IFNs that may be useful in the clinic against a variety of viral and neoplastic diseases.